Certain documents and in particular negotiable documents are printed with magnetic ink, ribbon or toner for machinery reading purposes. Negotiable documents are printed with what is known as the E-13B MICR font which includes a series of MICR (magnetic ink character recognition) symbols or characters. The magnetic ink printing of these characters provide an electronically readable signal to a machine for reading the document. However, if the signal strength is either too high or too low, the document cannot be read and is rejected from the machine reader. This presents serious problems to cheque printers who must therefore carefully scrutinize magnetic ink levels on the documents that they have printed.
In the past, secondary paper reference documents have been used as a means to calibrate test equipment for assessing whether or not a magnetic ink character recognition document, i.e. a MICR document has an appropriate level of magnetic ink to be readable by a machine reader. In particular, many years ago, the Bank Administration Institute in Chicago produced what were known as secondary reference documents having MICR encoded characters with an optimum signal strength for machine reading purposes. These documents, which were made from primary reference documents, had a known magnetic ink signal strength value, and were fed through test equipment which was then calibrated based on the secondary reference document. Over the decades, further secondary reference documents have been printed off of these primary reference documents and as will be appreciated, through aging of the primary reference documents the secondary reference documents have become less accurate.